Gun perforator firing system



Sept. 1942- R. w. LOHMAN 2,297,006

GUN PERFORATOR FIRING SYSTEM Filed March 7, 1941 INVENTOR 441 WL OHMA/YATTORNEY Patented Sept. 29, 1942 GUN PERFORATOB FIRING SYSTEM Ralph W.Lohman, South Pasadena, Calif., as-

signor to-Lane-Wclia Company, Los Angeles, Calm, a corporation ofDelaware Application March 1, 1941, Serial No. 382,209 9 Claims. (01.lea-0.5)

My invention relates to gun Perforator firing systems; that is, systemswhereby a multiple unit gun perforator suspended in a well casing from aconductor cable may be caused to fire its gun units in consecutive orderby electrical control to the single conductor cable. Among the objectsof my invention are:

First, to provide a gun perforator firing system wherein only a nominalamount 01' current'needs to be supplied through the conductor cable,thus causing only a small voltage drop thereover and thereby permittingthe use of a small conductor even though the cable length may be severalthousand feet Second, to provide a gun perforator firing system whereina predetermined time interval is obtained between the discharge of eachgun unit, merely by the steady application 01' a given voltage to theinput end of the cable or whereby the gun units may be fired atdiflerent time intervals by controlling or interrupting the supply ofcurrent, all from a remote station;

Third, to provide a system of this character which insures an adequateamount of energy to tire each of the cartridges contained in the gununit 01 the gun perforator, even though the fuses or resistances in thecartridges may vary in their resistance value or be comparatively low invalue and require a substantial current;

Fourth, toprovide a system of this character wherein high voltage surgesin the conductor cable are eliminated, so that the possibility ofdamaging the cable due to voltage surges is eliminated: and

Fifth, to provide a gun perforator firing system which eliminatesstepping switches or other moving parts in order toaccomplish sequentialfiring of the gun units.

With the above and other objects in view, as 'may appear hereinafter,reference is directed to the accompanying drawing, in whichithe wiringdiagram shows my firing system in association withthe gun units of a gunperforator.

Each gun unit for the gun perforator com-- prises a cartridge Icontaining an explosive and a fuse or ignition wire 2. The ignition wireis preferably grounded to the bullet 3 of the gun units which. in turn,is grounded to the body of the gun perforator (not shown). The other endof each cartridge is connected through a spark gap 5 and resistor 6 to acurrent supply line I. A condenser I is connected in a circuit parallel'I'heseveral cartridges l and their corresponding spark gaps 5,resistors 6 and condensers 8 from a suitable source 9 so that each ofthe condensers 0 are caused to charge. By graduating the value of theresistors 6 the rates at which the diflerent condensers charged difier.The several spark gaps function as switches and are designed to breakdown or pass current at a predetermined potential so that aseachcondenser reaches a predetermined potential the associated spark gapbreaks down, causing a sudden current surge directly to ground throughthe cartridge suflicient to raise the fuse 2 to incandescence andthereby ignite the explosive. If voltage is supplied at a constant valuefrom the source 9, the condensers will charge and then discharge intimed sequence which will be predetermined by the values of theresistors.

It should, of course, be noted that the resistors B may be equal invalue and the capacity of the condensers or capacitors 8 may be varied,or the condensers and resistors may be constant and the spacing of thespark gap 5 may be varied. In other words, by graduating either thespark gaps, the condensers or the resistors, the condensers may becaused to discharge in a predetermined timed sequence.

Ifit is desired to increase the time interval above that which ispredetermined by the resistors, it is merely necessary to. interrupt theflow of current at the input endof the cable after the discharge of agiven cartridge and again close the circuit when the desired time hasarrived.

tremely low; in fact, may be below the value necessary to ignite thefuses 2 collectively, or even one of the fuses individually.Consequently, the conductor cable which contains the conwith eachcartridge. and its spark gap, so that the cartridge and spark gap form adischarge circuit for the condenser.

ductor I may be relatively small and the conductor I may be ofcorrespondingly small diameter. This is particularly advantageous ingunperiorating deep wells, wherein the conductor cable may be as long as15,000 feet; necessarily,

the diameter of the conductor is limited and,

consequently, its resistance is comparatively great. The permissiblevoltage is also limited; consequently the amount of energy-that, can betransmitted over such a line is relatively small.

While this is a serious disadvantage in the operation of conventionalgun perforators, it offers no or capacitors become- The only possibleeffect of a high resistance cable is to increase the time required tocharge the condenser. Actually, the cable resistance is materially lowerthan the resistors I so that the possible range of resistance variationin the cable has no appreciable effect. v

It should be observed further that, due to the resistors 8, no currentor voltage surges take place inthe cable itself when the cartridges arefired, even though, the cable may have inductive characteristics andeven though a large amount of current is discharged through the sparkgaps v and their cartridges.

Various changes and alternate arrangements may be made within the scopeof the appended claims, in which it is my intention to claim all noveltyinherent in the invention as broadly as a the prior art permits.

I claim:

1. A firing system for gun perforators having -a cartridge provided withan electrically respon-.

sive ignition fuse, comprising: a capacitor;

- means for charging said capacitor; and means for discharging saidcapacitor through said car-- energy from said reservoir through saidignition fuse when the quantity of said electrical energy in saidreservoir reaches a predetermined value. 3. A firing system for gunperforators having a plurality of cartridges, each provided with anelectrically responsive ignition fuse, comprising: a plurality ofcapacitors corresponding to said ignition fuses; means for charging saidcapacitors; and means for discharging said capacitors through theirrespective ignition fuses in timed sequence. 1

4. A firing system for gun perforators having a plurality of cartridges,each provided with an electrically responsive ignition fuse, comprising:reservoirs of electrical energy located in the immediate vicinity of andcorresponding to said cartridges; means for supplying said reservoirswith electrical energy; and means for discharg-' handicap in theoperation of my present system.

ing the electrical energy from said reservoirs through theircorresponding cartridges and ignition fuses at time spaced intervals.

5. A firing system for gun perforators having a plurality of cartridges,each provided with an electrically responsive ignition fuse, comprising:a capacitor for each ignition fuse; means charging said capacitors atvarious predetermined rates; and means for discharging said capacitorsthrough their respectiveignition fuses as each capacitor reaches apredetermined charged condition, whereby said cartridges are fired attime spaced intervals corresponding to the predetermined rates at whichthey are charged.

a plurality of cartridges, each provided with an electrically responsiveignition fuse, comprising: a plurality of capacitors in close proximityto and electrically associated individually with said ignition fuses;means for charging said capacitors with current insufllcient to ignitesaid fuses directly; and means for discharging the accumulated energy insaid capacitors through said ignition fuses in timed sequence.

' 7. A firing system for gun perforators havin a cartridge provided withan electrically responsive ignition fuse, comprising: a capacitor inclose proximity to and electrically associated with said ignition fuse;means for charging said capacitor with current insufiicient to ignitesaid fuse; and means for discharging the accumulated energy in saidcapacitor through said fuse;

8. A method of firing the electrically responsive cartridges of a gunperforator, characterized by: charging at a slow and predetermined ratea. plurality of reservoirs of electrical energy electrically'associatedwith said cartridges; and discharging the electrical energy from saidreset RALPH W. LOHMAN.

6. A firing system for gun perforators having cartridges at timespacediin-"

